Air quality permit for NorthMet

Process background

On August 24, 2017, PolyMet submitted an air permit application to the Minnesota Pollution Control Agency (MPCA) for its proposed NorthMet project in northeastern Minnesota. Before submitting the air permit application, PolyMet was required to conduct air quality modeling using protocols approved by the MPCA. The results of the modeling were submitted with the air permit application and were incorporated into the final permit.

During the MPCA’s extensive permitting process, the agency scrutinized PolyMet’s draft air permit application following the standard review process which included detailed review of air emissions calculations, proposed operation and emission limits, fugitive dust control plan, and air quality modeling results.

In January 2018, the MPCA released a draft permit for public comment and held two public meetings jointly with the Minnesota Department of Natural Resources. The agency reviewed public comments and, as a result, updated the draft permit to include additional robust permit conditions based on comments received that further protect Minnesota’s air. The MPCA submitted a proposed permit and support documents to the Environmental Protection Agency (EPA) for review on October 25, 2018.

Permit issued

The MPCA issued the final air emissions permit to PolyMet on December 20, 2018.

In 2019, the air permit was appealed and the Minnesota Court of Appeals directed the MPCA to explain further its decision-making for issuing an air permit to address documents submitted to the agency in 2018 that discuss potential expansion scenarios. The Court of Appeals did not direct MPCA to reopen the administrative record.

On December 20, 2021, the agency released its revised findings and determined that the potential for future expansion does not support a decision to withhold issuance of the permit under Minnesota permitting rules. PolyMet’s air permit remains in effect.

Final documents

PDF icon FINAL PolyMet Air Quality Permit - Permit (aq5-36w)
PDF icon FINAL PolyMet Air Quality Permit - Appendices (aq5-36x)
PDF icon FINAL PolyMet Air Quality Permit - TSD (aq5-36y)
PDF icon FINAL PolyMet Air Quality Permit - TSD Attachments (aq5-36z)
PDF icon FINAL PolyMet Air Quality Permit Response to Comments (aq5-36aa)
PDF icon FINAL PolyMet Air Quality Permit Order (aq5-36bb)
PDF icon FINAL Findings of fact and conclusions of law (December 20, 2021)